Answer:
F = 9.81 [N]
Explanation:
To solve this problem we must use Newton's third le which tells us that the sum of forces on a body that remains static must be equal to one resulting from these forces in the opposite direction.
Let's perform a summation of forces on the vertical axis-y to determine the normal force N.
∑F = 0 (axis-y)
where:
m = mass = 4 [kg]
g = gravity acceleration = 9.81 [m/s²]
![N - (4*9.81)=0\\N = 39.24 [N]](https://tex.z-dn.net/?f=N%20-%20%284%2A9.81%29%3D0%5C%5CN%20%3D%2039.24%20%5BN%5D)
Now we know that the frictional force can be calculated using the following equation.
f = μ*N
where:
f = friction force [N]
μ = friction coefficient = 0.25
N = normal force = 39.24 [N]
Now replacing:
![f = 0.25*39.24\\f = 9.81[N]](https://tex.z-dn.net/?f=f%20%3D%200.25%2A39.24%5C%5Cf%20%3D%209.81%5BN%5D)
Then we perform a sum of forces on the X-axis equal to zero. This sum of forces allows us to determine the minimum force to be able to move the object in a horizontal direction.
∑F = 0 (axis-x)
![F-f=0\\F-9.81=0\\F= 9.81[N]](https://tex.z-dn.net/?f=F-f%3D0%5C%5CF-9.81%3D0%5C%5CF%3D%209.81%5BN%5D)
If the coefficient was smaller, a smaller force (F) would be needed to start the movement, this can be easily seen by replacing the value of 0.25, by smaller values, such as 0.1 or 0.05.
If the coefficient were larger, a larger force would be needed.
1 Is correct because James is going faster.
2 is correct because a faster speed on a position vs time graph will have a steeper slope
3 is correct as well.
The answer is 4 all of the above
Answer:
Explanation:
Given data
Ball one
mass m₁=3.0kg
velocity v₁=20 m/s
Ball second
mass m₂=2.0 kg
velocity v₂=12 m/s
First we need the speed of combined ball.Since the system conserves the linear momentum
So the combined velocity vt is:
Since the two balls 1 and 2 are moving in opposite direction
So
Substitute the given values
We have the equation for motion with constant acceleration is given by:
At initial position y₀=0 and vt=v-v₀
So
Answer:
Từ ánh sáng từ mặt trời đến nhiệt liên tục phát ra từ cơ thể chúng ta, có nhiều dạng bức xạ khác nhau. Tuy nhiên, khi nói đến bức xạ và nguy cơ ung thư, hầu hết mọi người đều nghĩ đến tia X và tia gamma.
Các nguồn tự nhiên của tia X và tia gamma bao gồm khí radon, chất phóng xạ trong lòng đất và các tia vũ trụ tấn công hành tinh từ không gian. Tuy nhiên, loại bức xạ này cũng có thể do con người gây ra. Tia X và tia gamma được sản xuất trong các nhà máy điện hạt nhân để sử dụng trong các xét nghiệm hình ảnh y tế, điều trị ung thư, chiếu xạ thực phẩm và máy quét an ninh sân bay với liều lượng nhỏ.
English:
From light from the sun to the heat that is continuously emitted from our bodies, there are many different forms of radiation. However, when it comes to radiation and cancer risk, most people think of X-rays and gamma rays.
Natural sources of X-rays and gamma rays include radon gas, underground radioactive material, and cosmic rays that strike the planet from space. However, this type of radiation can also be caused by humans. X-rays and gamma rays are produced in nuclear power plants for use in medical imaging tests, cancer treatments, food irradiation and airport security scanners in small doses.
It is because they are both renewable sources of energy
